Putnam Investments LLC again urged the U.S. Supreme Court to hear the pending challenge to its 401(k) plan, reminding the justices that they’ve twice asked the U.S. Solicitor General to address the issue presented by this case.

The central issue on appeal—which party has the burden of proving benefit plan losses—affects “virtually every” fiduciary breach lawsuit filed under the Employee Retirement Income Security Act, Putnam said in an April 1 brief. The federal appeals courts are split on this question, and the Supreme Court has asked the solicitor general to weigh in twice in the last four years, Putnam said....